Oven for coking of coal



Get. 20, 1942. F. IPUENING 2,299,253

OVEN FOR COKING OF COAL Filed Sept. 12, 1940 2 Sheets-Sheet l m yen tor,Oct. 20, 1942. F. PUENING OVEN FOR COKING OF COAL Filed Sept. 12, 19402 Sheets-Sheet 2 /n ventor 51w;

Patented Oct. 20, 1942 UNITED STATES Prii'il'i' DFFICE ApplicationSeptember 12, 1940, Serial No. 356,479 In Great Britain December 8, 19398 Claims.

This invention relates to the coking of coal and, although notexclusively, is particularly concerned with "by-product fire-brickovens, comprising movable, vertical heating walls formed internally withfiues in the shape of communicating horizontal passages disposed oneabove the other and through which are passed in series hot combustiongases, the coking chambers being arranged each between a pair of suchwalls.

In some known ovens of this type most of the air required for combustionis introduced into the lowest horizontal flue-passage as also is a majorportion of the fuel gas, for instance coal gas, this latter portionbeing sufilcient to raise the combustion air in the lowest flue-passageto the temperature desired for coke making. Thereafter the hotcombustion gases with an excess of air, pass horizontally through theentire length of the lowest fiue-passage'and then rise to the passageabove, where they receive a new injection of coal gas, thusre-establishing the desired coking temperature. After having traversedthe second flue-passage the gases turn up into the third passagereceiving a third injection of coal gas, and this process is repeatedseveral times until the gases finally reach the highest passage, whencethey are withdrawn through a vertical waste outlet conduit located nearthe end of the wall.

A great drawback of the type of oven described above lies in thepractical impossibility of withdrawing the burnt or partly burntcombustion gases from the top flue-passage without incurring leaks ofcoal distillate gas from the coking chamber into the vertical wasteoutlet conduit. The combustion gas volumes used in large coke ovens arevery considerable, and naturally require large diameter outlet conduits.A large conduit, however, weakens the structure of the brick wall,especially if those sides of the outlet conduit which face the coal arelarge. The danger arises, therefore, that coal distillate gas may leakthrough such large surfaces from the coking chamber into the outletconduit. The surfaces could of course be reduced in size by making thevertical outlet conduits narrower, but in this case higher velocitiesand higher suction have to be employed in the conduits, increasing inturn the danger of gas leaking into the conduits from the coking spaces.An improvement on this arrangement was made in the older ovens by makingthe heating walls between the coking chambers extremely thick, and bylocating the conduit as far as possibl away from the coking chambers.These thick walls were, however, expensive. Furthermore, even thickwalls do not prevent leakage of coal distillate gas into the outletconduit when the ovens have been in use for some time, because the coalgas produced in the coking chambers (depending upon the quality of thecoal) often builds up a considerable pressure before escapin into thecollecting main. Leaks of coal gases into the outlet conduits of olderovens were thus often considerable, resulting in serious economic lossesof by-products. These leaks also increased the waste heat temperature,at the expense of valuable surplus gas that might be sold at a profit.

An even more serious result, however, was the damage done to the outletconduits. In normal operation, temperature variations in the brickworkcannot be avoided when the oven doors are opened, the hot coke isdischarged and wet coal enters. These variations create movement in thebrick joints near the doors, finally disintegrating the mortar andcausing considerable leaks in the joints, so that coal distillate gas,due to the high pressure difference existing between the coking chamberon the one hand and the outlet conduit on the other tends to enter theoutlet conduit with some force, overheating, fusing and finallydestroying the conduits and the ovens.

These conditions therefore fixed a definite limit to this type of oven.In fact these ovens usually contained only five or six horizontalflue-passages superposed in each wall, because a greater number of suchpassages would require still more suction, making the operation of theoven quite unsafe.

With the present invention, however, ovens containing ten to twentysuperposed horizontal fluepassages and high coking speeds are possible.

It is an object of the present invention to effect improvements uponthis type of oven which are such that it can 'be used for modern largescale carbonisation at medium and low temperatures.

It is another object of the invention to provide an oven in which thehigh suction required in the outlet conduits and header is preventedfrom acting upon the joints of the coking chamber walls.

It is another object of the invention to ensure that distillate gasesleaking from the coking chamber pass into a heating flue where they mixare burnt with the heating gases.

It is another object of the invention to provide a heating wall in acoke oven in which the supporting means for internally positioned outletconduits or the brick portions intermediate the conduits and the wallsthat abut the walls of the coking chamber are insulated against thepossibility of providing communicating channels between the externalcoking chamber and the interior of said outlet conduits.

It is another object of the invention to provide a coking oven having acoking wall in which the horizontal flue-passages and the return bendsat the ends of the passages through which the gases rise upwardly frompassage to passage are so shaped and so heated that the buoyancy of thehot combustion gases rising in the wall becomes a maximum while theresistances of the flues opposed to the travel of these gases becomes aminimum, so that either no suction or only a small one is required atthe entrance tothe vertical outlet conduits for the withdrawal of thegases from the wall.

Other objects and advantages of the invention will become apparent fromthe description of a preferred form of the invention which will now bedescribed with reference to the accompanying diagrammatic drawings inwhich:

Figure 1 is a sectional elevation of a portion of a coke oven batteryshowing two coking chambers;

Figure 2 is a sectional elevation taken on the line 2-2 of Figure 1 andFigure 3 is a section on the line 3-3 of Figure 2. r

The coke oven illustrated comprises two coking chambers 5 and 6 each ofwhich is formed between a pair of movable walls 1 and 8 or 8 and 9respectively, built of refractory bricks jointed-together. An oven ofthis type is described and claimed in my co-pending patent applicationNo. 282,785 filed July 4, 1939 (2,240,575 issued May 6, 1941). Eachcoking chamber is sealed at top and bottom by doors l and Hrespectively, and at its sides by luting material I2, the doors l0 and Hbeing removable for charging and discharging, for which purpose also thewalls I, 8 and 9 are movable.

Each wall 8, for example is formed internally as a flue, indicatedgenerally at l3, through which heating gases are passed so as to heat upthe sides of the wall and thus to effect coking of coal charged into thecoking chambers and 6.

The flue i3 consists of superposed horizontal flue-passages l4, IE, I6,11 and I8 which are in communication with each other at alternate ends.All or most of the air for combustion is injected into the lowermostflue l4 together with a major portion of the fuel gas, through burnersl9 and 28 and passages 2| and 22 respectively, in the brickwork aroundthe lowermost flue. By this means any desired temperature, for example800 C. may be achieved in the lowermost flue. If desired, further fuelgas, and possibly a little air, may be injected into the lowest passage[4 through burners 23 and 24 and passages 25 and 26. The burning gasespass along the flue M to the left (Figure 2) and up intothe passageabove, around the carefully smoothed bend 2'17. It will be seen that thecombustion gases entering through the opening assist the upward motionof the burning gases due to their natural buoyancy. From the fluepassagel5 the heating gases pass around the carefully smoothed bend 28 into theflue-passage it above, being again assisted in their up- Ward motion bya relatively small quantity of fuel gas injected through the opening 29.From the flue I? the heating gases pass around the bend 31! into thetopmost flue-massage l8 being, if desired, again assisted in theirupward motion by fuel gas injected through the opening 3| which isshaped and designed to project the fuel gas on to the side face 39 ofthe flue, since greatest radiation occurs from the side faces and henceprovision may have to be made in this manner for keeping up thetemperature of these side faces. Openings 32 are provided in order togive opportunity for the introduction of additional fuel gas, whilstopening 33 is provided in order to heat up the dead end 34 which wouldnot otherwise receive any heating gases. As a general rule air isinjectedor drawn into the wall only through passages 2i and 22, allother burners either receiving no air or only suflicient air to initiatecombustion, utilising the air already injected through the openings 2!and 22. The burners 23 and 24 also serve merely to maintain thetemperature achieved by the gases issuing from the burners l9 and 26.

From the topmost flue-passage is the heating gases are withdrawn via apair of vertical conduits 35 and 3B which pass downwardly through thepartitions 31 between the flue-passages into a horizontal header 38which emerges from the Wall at the level of the lowest flue-passage 14,the header 38 being bolted to a pipe 39 leading to a chimney (notshown), in such a way as to permit motion of the wall.

As shown (in Figure 3) the vertical conduits 35 and 38 are circular butmight well be oval, in order to allow a freer passage for thehorizontally moving heating gases. Furthermore, as shown in Figure l,the horizontal header 38, which is of rectangular section, emerges atthe level of the lowest flue-passage, but it might equally well emergeat the level of any of the lower flue-passages, as for instanceindicated in Figure 2 at 3$A.

In practice, any number of exit conduits 35 and 36 may be used and theymay be disposed well to one end of the flue, whilst the header 38 mightemerge downwardly from the flue. Again, the flue-passages might bearranged other than horizontally without departing from the scope ofthis invention.

As the heating gases rise through the flue the resistance to flow, dueto friction and due to the changes of direction, act against the upwardmovement due to the natural buoyancy of "the gases, and the flue isdesigned so as to make these opposing forces roughly equal. Thus theflue-passages are shaped and rounded as at 21, 28 and for example, andthe burner passages 25, 29 and 3! for example, are so arranged to assistthe natural buoyancy and make the upward force if possible a littlegreater than the frictional resistance, so that a very small suction isestablished in the lowest flue l i, just suflicient to cause the air toenter the flue, while in the uppermost flue possibly a slight pressureis created. Subsequently, after having reached and traversed the topflue 18 the heating gases are drawn down through the conduits and 36into the horizontal header 33 and thence to the chimney, The suctionrequired at the inlet to the conduits 35 and 36 is therefore very smallor even zero, whilst maximum suction exists in the header 33,

In the case illustrated, the conduits 35 and 36 abut against thepartitions 3'! which in turn abut against the sides 4% (Figure 3) of thecoking chambers, whilst the header 38 is supported by brickwork atvarious points along its length, which in turn abuts against the cokingchamber walls. At these points it would be possible for distillate gaseswithin the coking chamber to leak through and continuous joints in thebrickwork directly into the conduits, which it is highly desirable toavoid for the reasons given above. To avoid such contingencies,therefore, passageways 4! are placed in the way of all joints 42 whichare continuous between the coking chamber and in communication withjoints 43 in the conduits. The passageways 4i communicate such joints 42with the flue l3 and thus by-pass into the flue I 3 any gases that mayleak through the joints 42, and in this way prevents their continuationonward to joints 43 directly. With respect to the header 38 wheresupported by brickwork abutting the coking chamber walls 40 passageways45 and 45: are provided in alignment with joints 44 for the same purposeas are passageways 4!,

As shown in Figure 2, the header 33 projects well clear of the cokingwall but even in this case the passageway 45 is arranged between theheader joints and the coking wall joints even though the former lieoutside the flue space; this is because although the header joints areoutside the coking wall it would be possible for distillate gases toleak along the brickwork 48 and into the conduit via those joints of theconduit which are external of the flue-space.

It will be seen that the major part of the exterior surface of theconduits 35 and 36 and of the header 38' lie in the flue-space so thatgases leaking from the coking chambers for the most part escape into theflue-space, as is desired, and it is only at locations where theconduits and the header, or the supports for them, abut against thecoking chamber walls that it is necessary to provide the passageways 4|,45 and 46, for bypassing possible leaks in the joints of the coking wallchamber from the joints in the conduits or header.

As has been stated above, with the known arrangements the pressure inthe header is always a negative one, whilst the pressure in thefluespace might be approximately zero and the pressure in the cokingspace is often a high positive one. Hence there is a strong tendency forthe distillate gases to leak out of the coking chamber into the conduitsand header. In the present arrangement, however, the provision of thebypassing passageways ensures that leaking distillate gases cannot forcetheir way directly into the conduits or header but will escape into thelarge flue-space l3 where they mix and are slowly burnt with the heatinggases, thus being utilised and avoiding damage by overheating to theconduits or the header. On the other hand in case of leaks in theheader, due to the high suction existing in it, the by-passingpassageways guarantee that burnt gases will enter the header and notcoal gases.

The external joint between the header 38 and the chimney pipe 39 issealed with luting material to avoid the entrance of air.

It will be seen that with this arrangement the pressure differencetending to force distillate gases from the coking chamber into theoutlet conduits and header is reduced to the pressure of the distillategas itself, the pulling force of the suction inside the header orconduits having ceased to assist. Furthermore, coal distillate gas, ifit still succeeds in much reduced quantit in forcing its way through thejoints of the coking wall, can now only enter into the combustion flueproper either directly or through the passageways 4l, 45 and 46, where,due to the large size of the flue, they cannot easily causesuperheating. The combustion flues are furthermore in contact with thecolder coal, and they are therefore not easily overheated. Furthermore,in these flues, the calorific value of the coal distillate gas would beusefully employed by being added to the combustion gases thus assistingthe coking process before entering the chimney.

The invention is applicable to brick-built ovens of the type described,whether the ovens or oven walls be stationary or movable.

All the waste heat conduits and headers are isolated from the cokingwalls themselves, in the sense that every joint in these pipes issurrounded b the combustion space or a space in communication with thecombustion space.

This isolation permits the use of very considerable suction inside theoutlet conduits and suction header, which in turn permits the members tobe given small diameters. The conduits and header are preferably locatedin the vertical centre plane of each wall, at an ample distance from theinterior surfaces of the two coking walls, so that the combustion gasesflowing through the horizontal fluepassages find ample passage on eachside of the pipes. The horizontal brick partitions between thesuperposedhorizontal fluepassages are built of large horizontal brickslabs touching each other, and a vertical outlet conduit may penetratethrough the centre of one of these slabs or between two adjoining slabs.In the latter case, there is a possibility of one or two joints of thevertical conduits being located between two adjoining slabs. Inconformity with the present invention, the high suction in the conduitis, however, prevented from continuing between the two slabs till itreaches the coking wall in contact with the coal, by the passageways 4!mentioned before.

The vertical outlet pipes are preferably not cemented together with thecoking wall brickwork, so that temperature expansions and contractionsof the brickwork or deformations due to coal pressure do not endangerthe pipes.

The conduits may be round or oval and a plurality of conduits areemployed in order to keep their diameter and the width and cost of theoven wall down.

The conduits are composed of individual relatively short sections whichpreferably rest upon each other, thus forming joints of sufficienttightness. Or the conduits may rest upon the horizontal brickpartitions. The lowest of the vertical conduit sections rests upon thehorizontal outlet header, which is securely held in place, so that leaksare avoided. If, however, small leaks occur, it is only combustion gasthat enters the conduits, so that no harm is done, especially as thetemperatures of the gases inside and outside the conduits arepractically equal.

The main principle that every joint in the outlet pipe system issurrounded by parts of the combustion flue-space is continued until theoutlet header has reached the outside of the heating wall where, if aleak occurs, air instead of coal distillate gas is drawn into theheader; or it is continued till the outlet header is so far removed fromthe coking space that due to the great thickness of interveningbrickwork, a leak of coal distillate gas into the header has becomeimpossible.

This system is therefore safe against coal gas leaks and so theemployment of a power driven fan creating a high suction in the outletconduits and header is possible. Thus large volumes of waste gases canbe removed from large but relatively thin and inexpensive coking walls.

The horizontal outlet header may be made short, with the result that oneof the vertical conduits may be located near the burners. Overheating ofthis conduit may be avoided by the provision of two burners, in eachflue-passage, straddling the conduit. Overheating may be further avoidedby locating one of these burners at a higher elevation. The conduit nextto the burners may also be made of a higher quality firebrick.

The burning of vertical gas flames below the return bends as at 25, 29and 3| has furthermore the advantage of supplying a greater amount ofheat to the internal narrow vertical faces of the walls. Thus, the endsof the flue-passages are well heated for their coking task andfurthermore additional buoyancy is created in the vertical return bends.

Further control may be achieved by providing adjustable dampers that maybe positioned partially to cover the vertical communication passagesbetween two superposed horizontal fluepassages, in case of excessivebuoyancy of the gases.

The new oven principle can of course be used also for the distillationof non-coking coal, oil

shale, lignite, peat, etc.

By virtue of the new arrangement, the serious objections to the oldovens with horizontal flues are overcome. Because the fear of highsuction in the outlet conduits and headers is eliminated, very largewalls can now be built, and their form can be improved by reducing theirhorizontal length and greatly increasing their vertical height, which isparticularly essential for ovens with vertical charging and dischargingof coal and coke. This greater height can now be subdivided into manyhorizontal flue-passages, each of which is equipped with one or moreburners, except perhaps the one or two top flue-passages. Theseimprovements produce the much better heat distribution essential formedium or low temperature coking in narrow coking chambers of forinstance 3" to 7 width whereby a great increase in the coking capacityof the ovens is obtained.

I claim:

1. In a coke oven, a hollow heating wall adjacent a coking chamber, saidheating wall being constructed of elements jointed together to comprisea system of internal heating flues, means for supplying heating gases tosaid flues, a conduit comprising jointed elements within said heatinwall for withdrawing waste heat therefrom, jointed elements within saidheating wall intermediate to said coking chamber and said conduit, saidconduit being spaced from the inper surfaces of said heating wall exceptfor certain of said jointed elements, the joints of said certain jointedelements being communicated with the heating flues by substantialpassageway means, whereby possible channels of joint communicationbetween the coking chamber and the interior of said conduit areintermediately bypassed into the said heating flues.

2. vIn a coke oven, a hollow heating wall adjacent a coking chamber,said heating wall being constructed of elements jointed together, aplurality of internal jointed baffle walls alternately spaced from theends of the said heating wall to form a single heating passageencompassing the area of an adjacent coking chamber, means for supplyingheating gases to said heating passage,

a conduit comprising jointed elements communicating with said heatingpassage for withdrawing waste heat therefrom, jointed elements withinsaid heating wall intermediate to said coking chamber and said conduit,said conduit being spaced from the inner surfaces of said heating wallexcept for certain of said intermediate jointed elements, the joints ofsaid certain jointed elements bein communicated with the said heatingpassage by substantial passageway means, whereby possible channels ofjoint communication between said coking chamber and the interior of saidconduit are intermediately bypassed into the said heating passage.

3. In a coke oven having a coking chamber, a heating wall adjacent thecoking chamber provided with a heating passageway, said heating wallbeing constituted by jointed refractory elements, a jointed refractoryoutlet conduit structure within said heating wall and communicating saidheating passageway with the exterior of the coke oven, said conduithaving a joint positioned within the boundary of said heating wall andbeing substantially spaced from the inner surfaces of said heating wall,and said heating wall having a substantial escape passagewaycommunicating the joints of said heating wall in the vicinity of thejoint f said outlet conduit to said heating passageway, thereby toby-pass into the heating passageway any gas escaping from the cokingchamber through the joints in the heating wall and prevent its entryinto said outlet conduit.

4. A coking oven, constructed of refractory elements jointed together,comprising a coking chamber, a hollow heating wall in position parallelto the coking chamber, the outer shell of the hollow heating wall beingconstructed of refractory bricks jointed together, means for supplyingheating gases to said hollow wall, a waste heat withdrawal conduit andheader-system built of refractory elements jointed together and locatedinside of said hollow heating wall preferably in its center plane,auxiliary jointed brickwork inside of said hollow heating wall,intermediate the waste heat withdrawal system and the outer shell ofsaid heating wall, said auxiliar brickwork serving to form baille wallsand supporting means for said withdrawal system, those joints betweenthe interior of the coking chamber and the interior of the withdrawalsystem, which are in contact with each other either directly or byvirtue of the intermediate auxiliary brickwork and which are thereforeadapted to draw distillate gases from the coking chamber into thewithdrawal flues being locally widened into substantial passagewayscommunicating with said flues.

5. A coking oven constructed of refractory elements jointed together,comprising a coking chamber, a hollow heating wall parallel to saidchamber, the outer shell of said heating wall being constructed ofrefractory bricks jointed together, a system of heating flues inside ofsaid wall jointed together, means for supplying heating gases to saidflues, a conduit and header system inside of said wall jointed togetherfor withdrawing Waste heat from said flues, auxiliary jointed brickworkinside of said wall intermediate the outer shell and the waste heatwithdrawal system for the formation of bafile walls and supporting meansfor said withdrawal system, and substantial passageway means provided inthe joints located between said coking chamber and said withdrawalconduit and header system, said passageway means being in communicationwith said heating flues and adapted to vent the pres sure condition thatmay extend into the joints from either the withdrawal conduit and headersystem or from the coking chamber.

6. A coking oven constructed of refractory brickwork jointed together,comprising a coking chamber between hollow coking walls jointedtogether, baffie walls in said coking walls jointed together and formingheating lines between them, means for supplying heating gases to saidfiues, waste heat withdrawal conduit and header means jointed togetherand substantially internal of said coking walls, auxiliary intermediatebrickwork jointed together for securing the location of said conduit andheader means inside and outside of said coking walls, substantialpassageway means being interposed in the joints of any of said jointedbrickwork between the coking chamber and the conduit and header means,said passageway means communicating with said fiues, and adapted toprevent direct flow of distillate gas from the coking chamber into theconduit and header means by venting it into said flues.

7. A coking oven constructed of refractory elements jointed together,comprising a coking chamber, a refractory coking wall, jointed togetherby coking wall joints, a plurality of refractory baiiie walls in saidcoking wall for forming heating flues inside of said wall, each of saidbaflle walls being jointed together by baflle wall joints, means forsupplying heating gases to said heating fiues, a waste heat withdrawalconduit and header system for removing waste heat from said heatingfiues to the exterior of said coking wall, said conduit and headersystem being jointed together by conduit joints, a portion of saidjoints being widened to form substantial passageway-means in all suchlocations where coking wall joints are in contact with conduit jointseither directly or indirectly by way of baflle wall joints, saidsubstantial passageway-means communicating with said heating flues.

8. A coking oven comprising a coking chamber, constructed of refractoryelements jointed together, a system of heating flues therefor, means forsupplying heating gases to said fiues, a conduit system constructed ofrefractory elements jointed together for withdrawing waste heat fromsaid fiues, said conduit system being substantially internal of saidheating fiues, and substantial passageway means, communicating with saidheating flues interposed between joints in the coking chamber and jointsof the conduit system at all places where the chamber wall joints are inthe vicinity of conduit joints.

FRANZ P'UENING.

